Hydrogen-producing fuel processing systems are adapted to produce, via chemical reaction, a product stream containing hydrogen gas as a majority component from at least one feedstock. Many such fuel processing systems are adapted to produce hydrogen gas from at least one liquid carbon-containing feedstock. In some fuel processing systems, more than one carbon-containing feedstock is utilized. In some fuel processing systems, water is also utilized as a feedstock. In some fuel processing systems, the one or more feedstocks are vaporized prior to being chemically reacted, or reformed, to produce the hydrogen-rich product stream.
The liquid carbon-containing feedstock is often an alcohol or hydrocarbon and is generally flammable. The liquid carbon-containing feedstock, either alone or in combination with water, is typically pumped or otherwise transported from a fuel supply or fuel source to regions of the fuel processing system where it is consumed. In some embodiments, the feedstock is consumed as a fuel for a burner or other heating assembly in addition to being used as a reactant for the production of hydrogen gas. Typically liquid (or other fluid) transport tubing provides conduits through which the feedstock flows. It is possible for leaks to occasionally occur, such as from the tubing, from couplings for the tubing, from couplings between other components of the fuel processing system, etc. Timely detection of such a leak, should it occur, is therefore desirable, especially in the context of flammable liquid carbon-containing feedstocks.